Medical needles are frequently used during surgical procedures in living bodies, for the purpose for example of performing punctures, injections, biopsies, etc. in a target located inside the body.
A medical needle is an elongate hollow tubular body.
In general, the needle has one bevelled end to facilitate passing through the tissues.
Depending on the procedure, the target may be located at a depth of 2 to 40 cm underneath the patient's skin.
However, the pathway which may be taken by the needle as far as the target located inside the body is not necessarily linear.
It is possible that there may be obstacles between the point of insertion of the needle and the target.
Such obstacles may be bones (through which the needle is unable to pass), sensitive organs (which risk being damaged by the needle), etc.
Also, it has been shown that a needle, at the time it is inserted, is subject to deformations.
This bending of the bevelled end therefore affects the pathway of the needle; the true pathway being different from the pathway intended by the practitioner.
In this respect, reference can be made to the work by Webster et al., “Nonhlonmic modeling of needle steering”, International Journal of Robotics Research, Sage Publications Ltd, 2006, 25, pp. 509-525.
The practitioner therefore seeks to steer the needle along a controlled pathway in relation to obstacles lying between the point of insertion and the target.
Guide devices intended to deform the needle so that it can bypass identified obstacles have therefore been developed.
Document WO 2010/020591 for example discloses a medical needle equipped with actuators attached to the outer surface of the needle or incorporated in the wall thereof via micro-manufacturing techniques.
Said actuators allow local stress to be applied to the needle so as to act on the curve of its distal end.
However the manufacturing of these miniature actuators remains difficult and costly.
Document US 2009/0270676 discloses a guiding device for a needle comprising an outer cannula of which a distal portion is able to be curved by a cable actuating system. The needle which is less rigid than the outer cannula conforms to the curve of the outer cannula as and when it advances therein and returns to a straight shape once its distal tip has reached past the distal end of the cannula.
The article by T. R. Wedlick et al., “Characterization of Pre-Curved Needles for Steering in Tissue”, 31st Annual International Conference of the IEEE EMBS Minneapolis, 26 Sep. 2009 presents research into determination of the influence of the radius of curvature and angle of curvature on the pathway of a needle whose distal tip is pre-curved.
However the tip of said needle is permanently curved, which limits the possibilities of modifying the pathway in relation to obstacles to be avoided.
The article “A steerable Needle Technology Using Curved Concentric Tubes”, P. Sears et al., Proceedings of the 2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, Oct. 9-15, 2006, pp. 2850-2856, describes a telescopic medical needle formed of a plurality of curved concentric tubes which allows a three-dimensional pathway to be imparted to the needle inside the patient's body to avoid bones or sensitive organs.
Depending on the respective rigidity of the different tubes, the curve of the needle can be imposed by the curve of the most rigid tube or by the combination of curves of tubes of equivalent rigidity.
However, said tube arrangement modifies the general curve of the needle and does not act specifically on the curve of the distal tip.
In addition this construction, for a given inner diameter, has the effect of increasing the outer diameter of the needle.
Yet it is sought on the contrary to minimise the outer diameter of the needle to limit trauma suffered by the body and to facilitate postoperative management.
There therefore subsists a need to design a device for guiding a medical needle that does not lead to increasing the diameter of the needle, which is easy and low cost to manufacture and which allows at least a localised curve to be imparted to the needle and/the insert.